Control interval size for selected devices

For each DASD, Table 1 identifies the control interval sizes that exactly fit one physical block for the data component. An X in the column indicates that for that device and the control interval size listed, the size of the control interval is equal to the physical block size of the data component.

If the chart does not show an X for a control interval size for a device, the control interval holds more than one block from the data component, and the control interval size listed is a multiple of the data component physical block size.

The control interval size is always equal to the index component physical block size.

Table 1. Control Interval Size
CI Size	Device
CI Size	3380¹	3390²	9345³
512	X⁴	X	X
1,024	X	X	X
1,536	X	X	X
2,048	X	X	X
2,560	X	X	X
3,072	X	X	X
3,584	X	X	X
4,096	X	X	X
4,608	X	X	X
5,120	X	X	X
5,632	X	X	X
6,144	X	X	X
6,656	X	X	X
7,168	X	X	X
7,680	X	X	X
8,192	X	X	X
10,240	X	X	X
12,288		X
14,336	X		X
16,384		X
18,432		X	X
20,480	X		X
22,528	X		X
24,576		X
26,624		X
Notes: 3380, all models 3390, all models 9345, all models X = VSAM-selected physical record size (equal to CI-size)

For more information on allocating space for a data set, see z/OS DFSMS Using Data Sets.